1. Field of the Invention
The present invention relates to display screens and more particularly to progressive display screens adapted to indicate the ground position of an aircraft with respect to a map and especially such a device which is placed on the aircraft and adapted to indicate the position of the aircraft within thirty miles of its exact location.
2. Statement of the Prior Art
In the past aircrafts had been provided with various types of screens indicating that the seat belts should be fastened and that smoking was not allowed during various periods during flight and subsequently various types of advertising screens were provided in which various operations were displayed for advertising purposes, but no aircraft had an aircraft position display having a map screen along with a position indicator varying with the location of the aircraft.
Harry C. Danaher holds U.S. Pat. No. 3,660,847, issued May 2, 1972, entitled Aircraft Position Display, in which he teaches a display device which indicates by a series of lamps on a map screen the location on the aircraft relative to a particular Omni transmitting station, with one of the lamps being lighted to indicate that Omni station to which the aircraft is nearest. A switching arrangement located in the cockpit is dialed to the same frequency number as the Omni receiver, so the pilot need not do any calculations or exert any effort to select which light to turn on. Further, by providing a memory unit a string of lamps may be lighted to represent the flight path and the lamps will remain on during the entire flight. The display consists of a matrix of lamps, which are positioned to coincide with the geographical locations of the Omni transmitting stations. An Omni receiver in the aircraft picks up the signal from a particular Omni station and the pilot is able to select the proper lamp to switch on.
Jean R. Stregemair holds U.S. Pat. No. 3,715,716, issued Feb. 6, 1973, entitled Progressive Display Screen, in which he teaches a device for indicating on a map screen the position of an aircraft to the passengers on the aircraft without the complexity of locating the position with the accuracy normally required in navigation. The device of Stregemeir is able to give only the approximate location of the aircraft during flight. A position indicator usually in the shape of a model aircraft is connected to a guide belt for guiding the position indicator along the map screen along a predetermined route of the aircraft.